fix: audio_frame_ms didn't work expectedly (#671)

* fix buf split logic

* we need to update len

Author: typester

livekit-ffi/src/server/audio_stream.rs

@@ -394,8 +394,7 @@ impl FfiAudioStream {
                     if let Some(target) = target_samples {
                         buf.extend_from_slice(&frame.data);
                         while buf.len() >= target {
-                            let data = buf.split_off(target);
-                            let mut frame_data = std::mem::replace(&mut buf, data);
+                            let frame_data = buf.drain(..target).collect::<Vec<_>>();
                             let new_frame = AudioFrame {
                                 data: Cow::Owned(frame_data),
                                 sample_rate,

livekit/src/plugin.rs

@@ -294,7 +294,7 @@ impl Stream for AudioFilterAudioStream {
 
             if this.buffer.len() >= this.frame_size {
                 let data = this.buffer.drain(..this.frame_size).collect::<Vec<_>>();
-                let mut out: Vec<i16> = Vec::with_capacity(this.frame_size);
+                let mut out: Vec<i16> = vec![0; this.frame_size];
 
                 this.session.process_i16(this.frame_size, &data, &mut out);